14/index.html

<html lang="en-US">
<head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width">
  <title>WebGL</title>
  <style>
    html, body {
      margin: 0;
      padding: 0;
      overflow: hidden;
      width: 100%;
      height: 100%;
    }
    canvas {
      width: 100%;
      height: 100%;
      display: block;
    }
  </style>
</head>
<body>
  <script type="text/javascript" src="https://rawgit.com/patriciogonzalezvivo/glslCanvas/master/dist/GlslCanvas.js"></script>
  <canvas id="canvas"></canvas>
  <script>
    const canvas = document.querySelector('#canvas');
    const sandbox = new GlslCanvas(canvas);
    const dpr = window.devicePixelRatio || 1;

    function resizeCanvas() {
      canvas.width = window.innerWidth * dpr;
      canvas.height = window.innerHeight * dpr;
      sandbox.setUniform('u_resolution', canvas.width, canvas.height);
    }

    document.addEventListener('DOMContentLoaded', () => {
      fetch(`/14/shader.frag`)
        .then(res => res.text())
        .then(fragmentText => {
          sandbox.load(fragmentText);
        });
    });

    function handleMove(event) {
      let x, y;
      const rect = canvas.getBoundingClientRect();
      
      if(event.touches) {
        const touch = event.touches[0];
        x = (touch.clientX - rect.left) * dpr;
        y = (touch.clientY - rect.top) * dpr;
      } else {
        x = (event.clientX - rect.left) * dpr;
        y = (event.clientY - rect.top) * dpr;
      }

      sandbox.setUniform('u_pointer', x, y);
    }

    function fullscreen(event) {
      const d = document.documentElement;
      if (d.requestFullscreen) {
        d.requestFullscreen();
      } else if (d.webkitRequestFullScreen) {
        d.webkitRequestFullScreen(Element.ALLOW_KEYBOARD_INPUT);
      }
    };
    document.body.addEventListener("dblclick", fullscreen);

    canvas.addEventListener('mousemove', handleMove);
    canvas.addEventListener('touchstart', handleMove);
    canvas.addEventListener('touchmove', handleMove);

    window.addEventListener('resize', resizeCanvas);

    resizeCanvas();
  </script>
</body>
</html>